In a security system, authentication is a method for distinguishing legal users from illegal users, and can be traditionally divided into three methods. The first authentication method is an identification (ID) and password input authentication method based on ‘What do you know?’ The second authentication method is a one-time password (OTP) and ID card input authentication method based on ‘What do you have?’ The third authentication method is a biometric authentication method based on ‘Who are you?’
A basic authentication method of confirming an ID for distinguishing a user and a password for authenticating the user in the authentication method based on ‘What do you know?’ is most widely used due to its cheap expense and simple application as compared with other authentication methods. The basic authentication method has been settled and used on the basis of all security authentication systems for a long period of time.
However, in the existing basic authentication method, since a user always uses the same ID and password, the ID and password are easily exposed to a peripheral person by accident as the number of times of using digital devices in public places is frequent in recent years. Further, the ID and password becomes a final target to be attacked by hackers who maliciously wiretap contents on wire/wireless communication, which results in many security problems and accidents. Furthermore, since a high-priced security system such as an OTP or biometric authentication is additionally used to solve such security problems and accidents, users are additionally burdened with not a little cost.